The correct answer is: Only assumption II is implicit.
The statement “If you are an engineer, we have a challenging job for you” is an implication. An implication is a statement of the form “If P, then Q.” In this case, P is “you are an engineer” and Q is “we have a challenging job for you.”
An implication is true if and only if P is false or Q is true. In other words, the implication “If P, then Q” is true if and only if either P is false or Q is true.
In the statement “If you are an engineer, we have a challenging job for you,” P is “you are an engineer” and Q is “we have a challenging job for you.” We know that P is true if and only if you are an engineer. We also know that Q is true if and only if we have a challenging job for you.
Therefore, the implication “If you are an engineer, we have a challenging job for you” is true if and only if you are an engineer or we have a challenging job for you.
Assumption I is “We need an engineer.” This assumption is not necessary for the implication to be true. The implication is true if and only if you are an engineer or we have a challenging job for you. We do not need to assume that we need an engineer for the implication to be true.
Assumption II is “You are an engineer.” This assumption is necessary for the implication to be true. The implication is true if and only if you are an engineer or we have a challenging job for you. If you are not an engineer, then the implication is false. Therefore, we must assume that you are an engineer for the implication to be true.
In conclusion, only assumption II is implicit in the statement “If you are an engineer, we have a challenging job for you.”