Access YouTube Video URL With YouTube Video ID

I'm currently working on a Web project that uses YouTube API.

I am completely unfamiliar with the API. So a lot of effort was needed for each line of code.

Using following code I can retrieve items in a playlist successfully:

https://www.googleapis.com/youtube/v3/playlistItems?part=id&playlistId=a&key=b

I receive a JSON file like this

{"kind": "youtube#playlistItemListResponse","etag": "\"Y3xTLFF3RLtHXX85JBgzzgp2Enw/Wz7cvzuMs_tcayBMxW0Zfi_seVE\"","nextPageToken": "CAUQAA","pageInfo": {"totalResults": "7","resultsPerPage": "5"    },"items": [        {"kind": "youtube#playlistItem","etag": "\"Y3xTLFF3RLtHXX85JBgzzgp2Enw/XqXewlxjMltQNRFVLLHsWClvl0o\"","id": "PLTkKeV68Awyfb3jUTWipVt1po4PRMLkegNZJmJyZT7sY"        },        {"kind": "youtube#playlistItem","etag": "\"Y3xTLFF3RLtHXX85JBgzzgp2Enw/YQ1fBRcQrALULNJik38Bg2I7od8\"","id": "PLTkKeV68Awyfb3jUTWipVt7aZNlECmRHa8IJ-kAFkmJs"        },        {"kind": "youtube#playlistItem","etag": "\"Y3xTLFF3RLtHXX85JBgzzgp2Enw/WV3S-Lii4Xys27YNFOVDVs_kvpM\"","id": "PLTkKeV68Awyfb3jUTWipVt3LY0ze6_BKXezp3JVY62uQ"        },        {"kind": "youtube#playlistItem","etag": "\"Y3xTLFF3RLtHXX85JBgzzgp2Enw/R-YeNXuuTjStx4OmGdDdYEpaXxw\"","id": "PLTkKeV68Awyfb3jUTWipVt7X1fr2iJ7kLfDFmJ_V_D0o"        },        {"kind": "youtube#playlistItem","etag": "\"Y3xTLFF3RLtHXX85JBgzzgp2Enw/IF2GQMx3AhGIntV_58dXWyH0Wtc\"","id": "PLTkKeV68Awyfb3jUTWipVt-vwlWFevATj923vR9_d5Ko"        }    ]}

If you take a look at JSON result,You'll see that each item has an ID.What should I do with this ID to get URL associated with that?