Answer:
C. ΔABC ~ ΔDEF
Explanation:
The operators in the different answer choices are used to describe different kinds of relations.
A. "almost equals" or "is approximately"
B. "equals"
C. "is similar to" (tilde operator)
D. "is congruent to"
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Additional comment
"Congruent" is used to describe geometrical figures in which all corresponding measures are identical. "Equal" generally refers to the relationship between algebraic or numerical values or expressions.
"Is approximately" is used to describe values that are the same within a suitable tolerance or error range. For example, 23.4 ≈ 23.352, where the value on the left has been rounded to the nearest tenth. (It is within 0.05 of the value on the right.)