In the following question, out of the four alternatives, select the alternative which best expresses the meaning of the idiom "be in two minds".

Introduction / Context:
Idioms are fixed expressions whose meanings cannot be worked out just by looking at the individual words. The phrase "be in two minds" is a common idiom in everyday English, especially in British usage, and it describes a mental state rather than a literal division into two minds. This question tests whether you know the figurative meaning of the idiom, not whether you interpret it literally.

Given Data / Assumptions:

• Target idiom: "be in two minds".
• Options:
  • Behave smart at sometime and stupid at other.
  • Unable to decide.
  • Having a split personality disorder.
  • Trying to do two things at the same time.
• The context is general English vocabulary, not medical or psychological terminology.
• The idiom is usually followed by "about something": for example, "I am in two minds about accepting the job."

Concept / Approach:
To "be in two minds about something" means to be uncertain or undecided, as if part of you wants to do one thing and another part wants to do something else. It does not literally refer to intelligence, madness, or personality disorders. Among the given options, "unable to decide" directly captures this sense of hesitation and internal conflict. The other options either over literalise the expression or attach unrelated ideas such as split personality or multitasking.

Step-by-Step Solution:
Step 1: Recall typical usage: "I am in two minds about moving abroad" means I cannot make up my mind about moving abroad. Step 2: Compare this with the option "Unable to decide." Being unable to decide is exactly what the idiom expresses: you have not reached a firm decision. Step 3: Consider option "Behave smart at sometime and stupid at other." This suggests inconsistent behaviour, not specifically indecision, so it does not match the idiom. Step 4: Consider "Having a split personality disorder." This describes a psychological condition and is not what normal speakers mean when they say they are in two minds about something. Step 5: Consider "Trying to do two things at the same time." This describes multitasking or over commitment, not indecision. "In two minds" is about choosing, not doing. Step 6: Since only "Unable to decide" matches the usual meaning, select that as the correct answer.

Verification / Alternative check:
Look at example sentences from everyday English: "She is in two minds about quitting her job," or "We are in two minds whether to go ahead with the purchase." In each case, speakers are not talking about intelligence, personality disorders, or doing two tasks; they are talking about uncertainty in making a choice. If you replace "in two minds" with "unable to decide" in such sentences, the meaning stays almost the same, confirming that this is the correct explanation.

Why Other Options Are Wrong:
"Behave smart at sometime and stupid at other" is wrong because it focuses on intelligence and behaviour, not decision making. "Having a split personality disorder" is wrong because it confuses a mental health condition with a figure of speech about ordinary indecision. "Trying to do two things at the same time" is wrong because it describes action, not a mental state of uncertainty.

Common Pitfalls:
Learners sometimes interpret idioms too literally, especially when they see words like "two minds" and think of medical or psychological conditions. Another pitfall is to pick options that sound dramatic rather than accurate. To avoid this, always think about how the idiom is actually used in sentences you have heard or read, and match that usage to the option that best captures the real-life meaning.

Final Answer:
"Be in two minds" means unable to decide.