All seeds need water, oxygen, and proper temperature in order to germinate. Experiment has shown that germinating seeds produce heat. 

The correct answer is B - Heat and water.

For a seed to germinate in a laboratory setup, two essential factors are required:

1. Water: Seeds need water to rehydrate and initiate metabolic processes.

2. Heat (or optimal temperature): Seeds require a specific temperature range to break dormancy and germinate.

The other options are not essential for seed germination:

A. Microbes: While microbes can influence seed germination, they are not a required factor.

C. Soil and manure: Seeds can germinate in a laboratory setup without soil and manure.

D. Heat and microbe: Microbes are not a necessary factor for seed germination.