Solution: Nested Queries and Fields

db.products.find(
  {
    $and: [
      { 
        $or: [
          { category: "Accessories" }, 
          { category: "Audio" }, 
          { category: "Cables" }
        ] 
      },
      {
        $or: [
          { 
            $and: [ 
              { price: { $lt: 12 } }, 
              { stock: { $gte: 50 } } 
            ] 
          },
          { 
            $and: [ 
              { price: { $gte: 20, $lte: 30 } }, 
              { rating: { $gte: 3.5 } } 
            ] 
          }
        ]
      }
    ]
  }, {_id:0, name:1, category:1, brand:1, price: 1, stock:1, rating: 1}
)