Select from options: Continue writing the next sentence.

How to make concrete planters
1-choose your molds.
You will need an outer mold and an inner mold of same shape but different size.
- the smaller mold should nestle inside the larger with a gap of about 2 inches or 5 cm.

Pick your answer from: A. If you use 3 or 4 molds and the inner has a gap of roughly 6 inches (15. 2 cm) it will not last long.; B. - the outer molds should be the same size but bigger. - press the inner molds in between the inner molds and press them firmly.; C. The gap between molds will be the thickness of your planter's walls. If your planter will be any larger than 2 feet (0.6 m) by 2 feet (0.6 m), the walls should be 3 inches or 7.5 cm thick.; D. - the molds are the most reliable size for building clay planters. Ensure you have enough of them before proceeding.;
Answer:
C.