Electronegativity is a measure of the tendency of an atom to attract a bonding pair of electrons. This property increases across a period from left to right in the periodic table and decreases down a group. To determine the correct order of electronegativity for the given elements (C, N, Si, P), we need to consider their positions in the periodic table:

• Carbon (C) and Nitrogen (N) are in the second period. Carbon is in Group 14 and Nitrogen is in Group 15.
• Silicon (Si) and Phosphorus (P) are directly below Carbon and Nitrogen in the periodic table, belonging to the third period, in Groups 14 and 15 respectively.

According to the trends in electronegativity:

• Within the same period (e.g., Period 2), as we move from left to right (from Carbon to Nitrogen), electronegativity increases.
• Within the same group (e.g., Group 14 from Carbon to Silicon), as we move down the group, electronegativity decreases. The same applies to Group 15 (from Nitrogen to Phosphorus).

Therefore, considering their positions:

• Nitrogen (N) has a higher electronegativity than Carbon (C) because they are in the same period (Period 2) with N to the right of C.
• Carbon (C) has a higher electronegativity than Silicon (Si), its counterpart in the period below (Period 3).
• Similarly, Nitrogen (N) has a higher electronegativity than Phosphorus (P).
• Between Silicon (Si) and Phosphorus (P), which are both in Period 3, P (being to the right) has a slightly higher electronegativity than Si.

Thus, if we order these elements by increasing electronegativity, it would be:

$$ \text{Si} < \text{P} < \text{C} < \text{N} $$

Looking at the available choices:

• Option A (C, N, Si, P) - Incorrect: Here, it suggests C has a lower electronegativity than N but incorrectly orders Si and P.
• Option B (N, Si, C, P) - Incorrect: Wrong sequence, does not consider correct trends.
• Option C (Si, P, C, N) - Correct: This option correctly represents the increasing order of electronegativity.
• Option D (P, Si, N, C) - Incorrect: Completely reverses the electronegativity trend.

The correct answer is Option C.