the meaning of 'pick up'
The sentence below comes from a book, SAT Power Vocab.
https://books.google.co.kr/books?id=7Xk0AQAAQBAJ&pg=PA196&dq=%22The+book+I+was+reading+wasn%27t+terribly+engaging%3B+in+fact.+it+was+one+of+those+books+that+is+hard+to+pick+up.%22&hl=en&sa=X&redir_esc=y#v=onepage&q=%22The%20book%20I%20was%20reading%20wasn%27t%20terribly%20engaging%3B%20in%20fact.%20it%20was%20one%20of%20those%20books%20that%20is%20hard%20to%20pick%20up.%22&f=falseThe book I was reading wasn't terribly engaging; in fact. it was one of those books that is hard to pick up.I'd like to ask what the underlined 'pick up' means.
I looked up a dictionary.
It seems to mean #1 in a way, but I cannot rule out #5b in another.
#1 makes the sentence humorous, but just because of that the meaning makes a bit odd without other clue. Just one sentence makes the context hard to grasp.
#5b doesn't seem to fit exactly right, because when I first read that sentence I thought 'pick up' means 'understand'. However, I cannot rule out this meaning.
Help me out of this dilemma.
Regards.
http://www.thefreedictionary.com/pick+up 1. To take up (something) with a hand or other body part or with an instrument: ?
Could you pick up that book? ?
The dog picked up the bone in its mouth.
2. To collect or gather: ? picked up some pebbles.
3. To tidy up; clean: ? picked up the bedroom.
4. To take on (passengers or freight, for example): ? The bus picks up commuters at five stops.
5. Informal
a. To acquire casually or by accident: ? picked up a new coat on sale.
b. To acquire (knowledge) by learning or experience: ?
picked up French quickly.