Find the Missing First Term in Sequence: ?, 2, -1, -4, -7, -10

To solve this problem, follow these steps:

• Step 1: Determine the common difference $d$ of the sequence.
  The sequence given is $2, -1, -4, -7, -10$. Calculate the difference between consecutive terms:

$d = -1 - 2 = -3$ (confirming $-4 - (-1) = -3, -7 - (-4) = -3, -10 - (-7) = -3$).

• Step 2: Use the common difference to find the term before the first known term (2).

We subtract the common difference from the first known term to find the missing term before it:
The first known term is 2. Calculate $2 - (-3)$:

$? = 2 + 3 = 5$.

Therefore, the first term of the sequence is $\boxed{5}$.

Reviewing the multiple-choice options, the correct choice is $\boxed{5}$, which corresponds to choice (3): $5$.