DNA is made up of two strands that are complementary to each other. The base pairing rules state that adenine (A) pairs with thymine (T), and cytosine (C) pairs with guanine (G). Using these rules, we can determine the sequence of the complementary strand of the given DNA sequence ATGCTTCA. Here's the pairing for the given sequence:

A (adenine) pairs with T (thymine)

T (thymine) pairs with A (adenine)

G (guanine) pairs with C (cytosine)

C (cytosine) pairs with G (guanine)

T (thymine) pairs with A (adenine)

T (thymine) pairs with A (adenine)

C (cytosine) pairs with G (guanine)

A (adenine) pairs with T (thymine)

So, the complementary base sequence to the given DNA strand ATGCTTCA would be:

1. A pairs with T

2. T pairs with A

3. G pairs with C

4. C pairs with G

5. T pairs with A

6. T pairs with A

7. C pairs with G

8. A pairs with T

Putting it all together, the complementary sequence is: TACGAAGT. Therefore, the correct answer is: Option B - TACGAAGT